Abstract

The reversal mechanisms of graded anisotropy FePtCu films have been investigated by alternating gradient magnetometer (AGM) and magneto-optical Kerr effect(MOKE)measurements with first-order reversal curve (FORC) techniques. The AGM-FORC analysis, which clearly shows the presence of soft and hard components, is unable to resolve how these phases are distributed throughout the film thickness. MOKE-FORC measurements, which preferentially probe the surface of the film, reveal that the soft components are indeed located toward the top surface. Combining AGM-FORC with the inherent surface sensitivity of MOKE-FORC analysis allows for a comprehensive analysis of heterogeneous systems such as graded materials.

Received 19 August 2010Accepted 24 October 2010Published online 15 November 2010

Acknowledgments:

Support from The Swedish Foundation for strategic Research (SSF), The Swedish Research Council (VR), the Göran Gustafsson Foundation, and the Knut and Alice Wallenberg Foundation is gratefully acknowledged. V.B. thanks the Blanceflor Boncompagni–Ludovisi Foundation. J.N. thanks the Catalan DGR (Grant No. 2009SGR1292) and the Spanish MICINN (Grant No. MAT2010-20616-C02) projects for partial financial support. J.Å. is a Royal Swedish Academy of Sciences Research Fellow supported by a grant from the Knut and Alice Wallenberg Foundation.